Possible role of interleukin-10 (IL-10) and CD40 ligand expression in the pathogenesis of hypergammaglobulinemia in human immunodeficiency virus infection: modulation of IL-10 and Ig production after intravenous Ig infusion.

The mechanisms leading to polyclonal hypergammaglobulinemia in patients with human immunodeficiency virus (HIV) infection are not well understood. In light of the important role of interleukin-10 (IL-10) and the interaction between CD40 and CD40 ligand in the normal regulation of B-lymphocyte function and Ig production, we examined these parameters in 24 HIV-infected patients. Both plasma IL-10 levels and the percentage of CD4(+) and CD8(+) lymphocytes expressing CD40 ligand were significantly higher in the patients than in the 10 blood donor controls. Serum IgG correlated positively with circulating IL-10 levels and the percentage of CD4(+) lymphocytes expressing CD40 ligand. Furthermore, a single bolus infusion of intravenous Ig (0.4 g/kg) in 8 HIV-infected patients caused a further increase in IL-10 levels in plasma and an increase in both IL-10 and IgG production in peripheral blood mononuclear cell cultures. In another patient group (Wegener's granulomatosis) receiving a single bolus infusion of intravenous Ig, a similar increase in plasma IL-10 levels was found, suggesting that this may be a general effect of intravenous Ig. In patients with HIV infection, our data suggest that a vicious cycle may be operative where high endogenous Ig levels may enhance IL-10 production that, in turn, leads to higher Ig production.